In the field of microwave plane antennas, or flat antennas, it is well known that there are typically two types. The first type generally includes antennas with small electrical dimensions with respect to the wavelength. This type of antenna is distinguished by a wide-band. Antennas of the second type define a large electrical length and typically operate using a standing wave. This type of antenna is distinguished by a narrow band.
Other flat antennas have been developed to overcome problems in the art. Typical of these are those antennas disclosed in the following U.S. Patents:
______________________________________ U.S. Pat. No. Patentee(s) Issue Date ______________________________________ 3,972,050 C. M. Kaloi July 22, 1976 3,995,277 M. Olyphant, Jr. Nov. 30, 1976 4,644,361 Y. Yokoyama Feb. 17, 1987 4,933,679 Y. Khronopulo, et al. June 12, 1990 ______________________________________
and by T. Makinoto, et al., in UK Patent Application Number 2,170,051A, published Jul. 23, 1986. The antenna in accordance with the Yokoyama ('361) patent consists of unit rectangular elements with a fixed length (equal to one quarter of the wavelength) and a fixed width (equal to one half of a wavelength). The antenna in accordance with the Kaloi ('050) patent represents an antenna array formed from a plurality of radiating elements. The shape of the Kaloi elements is similar to the shape of the elements disclosed in the '361 patent. The device disclosed by Olyphant, Jr. ('277) is described as being provided with radiating elements which are significantly different from the present invention. The antennas described in the '679 patent issued to Khronopulo, et al. and in the UK patent ('051 A) issued to Makinoto, et al., each consist of a plurality of stripline antennas combined into an antenna array defined by a specific height above an integral metal base. Each stripline antenna is defined by a plurality of consecutively connected radiating elements. The radiating elements are each identical to the others. Each stripline antenna represents a section of an unbalanced stripline, with the configuration changing step-by-step along the radiating element symmetrically in respect to its longitudinal axis. The distance between the neighboring steps is considerably smaller than the working wavelength. The stripline antennas forming the array are connected with a selected period by one end to an excitation device representing a section of an unbalanced stripline. There are densely ranged stripline stubs on the side of the excitation device opposite to the stripline antennas.
This type of antenna provides for a wide working frequency band and has the maximum directed along the normal to the surface of the antenna. However, the application of a plurality of elements having a step form decreases the efficiency of the antenna due to losses related to spurious radiation and reflections on heterogeneities. Further, the use of identical radiating elements with consecutive feeding leads reduces the coefficient of utilization of the surface of the antenna. This is due to the drop of the amplitude of radiation along the length of the antenna.
Yet another microwave stripline antenna is disclosed in Russian patent 1730697-A1, issued on Apr. 30, 1992 to inventors common to the present invention. This patent, however, does not teach the use of a gradual junction or a radial bend. Instead, the Russian patent teaches an antenna that transfers high frequency energy from an excitation device to stripline antennas in a centralized path of the antenna through a transverse slot formed in the metallic base of the antenna. The transverse slot runs along the lateral axis of symmetry of the metallic base.
Therefore, it is an object of this invention to provide a means for manufacturing stripline antennas having high efficiency with large electrical dimensions.
It is another object of the present invention to provide a means for manufacturing a stripline antenna having a high amplification capability.